From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49011) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gX1Ue-0000u3-Ni for qemu-devel@nongnu.org; Wed, 12 Dec 2018 05:11:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gX1Uc-0003MZ-7i for qemu-devel@nongnu.org; Wed, 12 Dec 2018 05:11:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37282) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gX1Ub-0003Lg-Ue for qemu-devel@nongnu.org; Wed, 12 Dec 2018 05:11:50 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4F1232D7E4 for ; Wed, 12 Dec 2018 10:11:49 +0000 (UTC) From: Markus Armbruster Date: Wed, 12 Dec 2018 11:11:40 +0100 Message-Id: <20181212101145.3496-7-armbru@redhat.com> In-Reply-To: <20181212101145.3496-1-armbru@redhat.com> References: <20181212101145.3496-1-armbru@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL 06/11] monitor: prevent inserting new monitors after cleanup List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= From: Marc-Andr=C3=A9 Lureau monitor_cleanup() is one of the last things main() calls before it returns. In the following patch, monitor_cleanup() will release the monitor_lock during flushing. There may be pending commands to insert new monitors, which would modify the mon_list during iteration, and the clean-up could thus miss those new insertions. Add a monitor_destroyed global to check if monitor_cleanup() has been already called. In this case, don't insert the new monitor in the list, but free it instead. A cleaner solution would involve the main thread telling other threads to terminate, waiting for their termination. Signed-off-by: Marc-Andr=C3=A9 Lureau Reviewed-by: Markus Armbruster Message-Id: <20181205203737.9011-7-marcandre.lureau@redhat.com> Signed-off-by: Markus Armbruster --- monitor.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/monitor.c b/monitor.c index a1329d8a86..d353c0e645 100644 --- a/monitor.c +++ b/monitor.c @@ -263,10 +263,11 @@ typedef struct QMPRequest QMPRequest; /* QMP checker flags */ #define QMP_ACCEPT_UNKNOWNS 1 =20 -/* Protects mon_list, monitor_qapi_event_state. */ +/* Protects mon_list, monitor_qapi_event_state, monitor_destroyed. */ static QemuMutex monitor_lock; static GHashTable *monitor_qapi_event_state; static QTAILQ_HEAD(mon_list, Monitor) mon_list; +static bool monitor_destroyed; =20 /* Protects mon_fdsets */ static QemuMutex mon_fdsets_lock; @@ -4538,8 +4539,21 @@ void error_vprintf_unless_qmp(const char *fmt, va_= list ap) static void monitor_list_append(Monitor *mon) { qemu_mutex_lock(&monitor_lock); - QTAILQ_INSERT_HEAD(&mon_list, mon, entry); + /* + * This prevents inserting new monitors during monitor_cleanup(). + * A cleaner solution would involve the main thread telling other + * threads to terminate, waiting for their termination. + */ + if (!monitor_destroyed) { + QTAILQ_INSERT_HEAD(&mon_list, mon, entry); + mon =3D NULL; + } qemu_mutex_unlock(&monitor_lock); + + if (mon) { + monitor_data_destroy(mon); + g_free(mon); + } } =20 static void monitor_qmp_setup_handlers_bh(void *opaque) @@ -4634,6 +4648,7 @@ void monitor_cleanup(void) =20 /* Flush output buffers and destroy monitors */ qemu_mutex_lock(&monitor_lock); + monitor_destroyed =3D true; QTAILQ_FOREACH_SAFE(mon, &mon_list, entry, next) { QTAILQ_REMOVE(&mon_list, mon, entry); monitor_flush(mon); --=20 2.17.2